Tomorrow is the Solemnity of the Nativity of St. John the Baptist. Observance of the solemnity begins with First Vespers (Evening Prayer I) in the Liturgy of the Hours on June 23, and a special Vigil Mass before or after First Vespers. The liturgical day is from midnight to midnight in the Church's observance, except for Sunday and solemnities which begin with the evening of the preceding day. There are many customs and traditions connected with the Vigil of the the Birth of St. John the Baptist, often referred to as "Midsummer's Eve."